Validation of an online system for the continuous monitoring of tree water status for sustainable irrigation managements in olive (Olea europaea L.)

The inversion of the daily curve of the leaf patch clamp pressure probes reading was observed when Ψswp decreased under the value of −2.2/−2.5 MPa suggesting the possibility to use this indicator to detect high water stress levels. Anyway, considering that at this level of stress the plants had already strongly reduced the gas exchanges by 40-50% with respect to their values at Ψswp above −2 MPa, with consequence on carbohydrate production that can affect productivity, rise the need to find other indicators that enable to differentiate water status at lower stress levels. From the result of this work a promising indicator seems the relative increase of the daily minimum value of the leaf patch clamp pressure probe readings, as suggested by its correlation with Ψswp.